Telephone repeater



Jan. 31, 1933. J. P. LOWE TELEPHONE REPEATER Filed Feb. 24, 1932 able conditions,.

Patented Jan. 31, 1933 UNITED STATES JAMES P. LowE, or LIMA, PERU TELEPHONE nnrnarnn Application filed February 24,1932, Serial No. 59 4,836,'an 1 in Great Britain January 80, 198 1.

' This invention relates to improvements in telephone repeaters and has for it's primar object to provide a system whereby speec ent in use, therepeater consist of two line balances and the repeaterproper, 7 one line balance being connected to either half of the line, and the repeater arranged so that speech currents amplified divide equally between the balance and the line, and by a differential arrangement of coils render the incoming signals inoperative.

Such an arrangement,

ent on an accurate balancebetween the line and line balance, thus making repetitionon overhead lines very diflicult, due'to the variparticularly with long-distance lines.

The invention provides an arrangement of 7 transformers, so arranged and connected that speechsignals may be amplifiedfin either direction on a long-distance line without interaction between up and down sides, and according to the invention speech currents on one side of the repeater are received by a transformer comprising two bridges, each bridge being divided int two arms, each arm consisting of a primary and associated secondary winding. One arm in each bridge is arranged to neutralize the corresponding arm in the other bridge, to balance unwanted 3'5 speech currents, the other two arms being arranged to pass the speech currents via a suitable transformer or transformers to the amplifying device. Identical transformer arrangements are provided on both sides of .40 the repeater so that the device functions either way.

The amplified currents are passed via suitable output transformer, to both bridges of the transformer on the other side of the repeater, the currentdividing equally between the four arms, two of which neutralize each other, the other'two sending the amplified speech currents to the line.

When speech is being received, the bridge 750 is out of balance to the input transformer,

thus allowingspeech currents to pass to the inputtransformer. When, however, amplified currents are passed to the line, the bridge PATENT OFFICE-Q I is perfectly balanced to the input transformer, therefore no interaction can takepla'cebetween the up, peater. y r

The repeater is not balanced to the lines on and down sides of the re either side, the balancing action functioning M purely within the repeater, and is quite in dependent of the length of line on either side of the repeater. K Y

For a ready understanding of theinvention, reference will now 'be made to the ac- V companying drawing,,wherein however, is dependp g V 'cllcult arrangement of a repeater in accord- Figure 1 is a diagrammatic View of the transformers having primaries a, a2, w a,

and their associated secondaries as, 008,:208, it's, of which a and ware in one part of'the system and a and winthe other part. The primaries w and a" are connected in such manner that input currents in these two windings produce E.v F.s in theirfsecondaries of opposing directions sothat no current is produced 'in'thesecondary' circuit of this part of the transformer system. On the other hand, primaries a and a are connected in such manner that input currents produce'assisting E. M. 'F.s in the secondary circuit of this part: The current "in .this secondary circuit passes to four primary.

windings b of an auxiliary transformenf second auxlllary transformer having four [primary windings b" is connected to windingsw'mas. v V

Four secondary windlngs b8 and 6's are inductively coupled to the primary coils 1),

7)v and connected in series with a resistance which is connected to an amplifying equipment, such as is usually usedin'current re-V pass to the primary coils of output transformers e, the secondary coils of which are connected to the primary coils of transformers b, b. one transformer e is connected to the midpoints of the primary windings of transformer b so thatcurrent in one pair of the 7 primary windings tends to induce secondary currents in the associated secondaryin op- .posite direction to that which current in the otherpair ofthe primary windings tends to produce in the other secondary. The same applies to the other transformer e. -The amplified currents which have divided through the primary sections of 5 pass throughsecondaries as'and'ws and the current in each of these two windings" produces i an F, in its associated primary. These two F.s are opposite in sense and therefore no current is produced. The same ,applies as regards secondaries ms' and as, that is each produces an E. M. F. in its associated primary; Due, however, to the man- ;ner in which primaries a3 and a are con .nected these E. M. F.s assist each other and am hfied current passes to line.

peech currents before amplifications .passfrom the line through a transform- .er having windings P, S to the transformer primary windings (1,00, m, a, The-current flowing in the primary windings' a and m induce voltages in their respec tive secondary windings which oppose each other in the circuit including .the four lwindings, b, b, b, b, so that no exciting cur- .rent flows through these windings, hence no voltage is induced in the secondary windmgs 68, "b8. Now currents flowing through primary windings ac, a induce voltages in their secondary winding as and 00's which aid each other in the circuit including the primary windings b, b, b, b andthe current which flows therethrough' induces aiding voltages in the secondarywindings bs,

1bsandthesevoltages in turn cause current to pass through the circuit including thesaid resistance CI and primary 0 of the input transformer whereby they are delivered to .the amplifying equipment.

In an alternative arrangement, as illustrated in Fig.2 of the drawing, primaries w and m, and secondaries wsand w s constitute one transformer having a common core and a, as, a's may also constitute one transformer: or may be two transformers. In this case, it is necessary to reverse the direction of secondary as with referenceto the two lower windings b, as illustrated in Fig. 20f

The secondary winding of the drawing. Itis also necessary to reverse the direction of the secondaries 19's with reference to the secondaries 68, that is the lower end of the lower bs, is connected to the lower end of the lower be.

In this arrangement, input current in primaries a and a produce current in their respective secondaries but, owing to the man nor in which primaries a; and a/ are connected, these latter are unable to produce any flux in the core. The secondaries ms and ms act merely as dead resistance to the current in as and as respectively. The currentspass through primaries ,b. and .6 respectively-and producecurrent's inthe secondariesbs, b's, these currents passing to the amplifying device. The speech currents, after amplification pass, as before, to' trans formers e andftend to induce secondarycur rentsin opposite directions in} the secondary windings 68,128'. The amplified currents,

which have: divided through the primary systems of 5, pass through secondaries as and tendto produce opposingifluxes; in their common core with the result that'no flux is pro duced and consequentlyjno currents are pro- ,ws,as and ms. The currents in ms and 00's 1 190 duced in primaries w andw. The currents in secondaries as and as are able,-due to'the manner in which as is connected withregard zformedfl'y'declm'e what "-Iclaim is 1.-fIn telephone repeaters, the provision of v a transformer comprising two bridges, each bridge being divided'into twoarms, "each arm. consisting of a primary and associated secondary winding, one arm in each bridge being arranged to neutralize the .cor-

responding arm in the other'bridge, to balance' unwanted speech currents, the other two arms being arranged to pass incomingspeech currents via an input transformer to an amplifylngdevlce."

* 2.'In telephone repeaters, the; provision of a transformer comprising two bridges, each br dge being dlvided 'intotwo arms,eacharm consisting of a primary and associated sec.-

ondary winding, one arm in each bridge belng arranged to neutralizethe corresponding'arm in the other bridge, 1 .0 balance'unwanted speech currents, the other two arms being arranged to pass incoming speechcurrents via an lnput transformer to an amplifying device, an intermediate, transformer for each bridge consisting of two pairs of primarywindings, the two windings of each pair being arranged infiseries, one pairbeing connected to :one side of each'secondary arm of theibridge, and the other-pair. being connected to tlie remaining side of said secondary arms so that all are connected in series, a pair of secondary coils for each bridge coupled to the said primary windings, said secondary coils of the two bridges being connected in series with one another and with the primary of the input transformer and output transformer for each bridge, the secondary of which has its respective sides connected to the centres of the pairs of primary windings of the intermediate transformer, the primaries of said output transformers being connected in series in the output circuit of the amplifier.

3. In telephone repeaters according to claim 1, the provision at each side of the repeater of a transformer interposed between the two bridges and the line, the windings of which have an impedance matchedto that of the bridges and line respectively.

4. In a telephone repeater according to claim 2, the provision at each side of the repeater of atransformer interposed between the two bridges and the line, the windings of which have an impedance matched to that of the bridges and line respectively.

5. A signal transmission system comprising two one-way paths, a two-way path and 7 means for joining said one-way paths electrically to said two-way path and for rendering them electrically independent, said means comprising a plurality of transformers having their primaries connected to the two-way path and their secondaries connected through balanced circuits to the oneway paths.

6. In telephone repeaters, a transformer system divided into two parts, each part hav ing two primary windings and two secondary windings, the primary windings being so arranged with reference to each other and to their associated secondary windings that input speech currents in two of the primary windings produce no currents in their associated secondaries and that amplified speech currents in two of the secondary windings produce no currents in their associated primary windings. V

7. In telephone repeaters, a transformer system divided into two parts each part having two primary windings and associated secondary windings, one primary of one part being so arranged with reference to the other primary of the same part and to their associated secondaries that currents in the said two primaries produce no currents in the said secondaries, the two primary windings of the other part being so arranged with reference to each other and their associated secondaries that currents in the said two primaries produce currents in their associated secondaries.

8. In telephone repeaters, a transformer system divided into two parts each art having two primary windings and assoclated secondary windings one primary of one partbe ing so arranged with reference to one primary of the other part and to their assoclated secondaries that currents in the said two prihis signature.

JAMES P. LOWE. 

